This section will contain minor spoilers, so skip this if you're against them [it's arguably minor, it's vague overviews -- no specific references except one bene one, just the gist of the arc. I would recommend to read this, since it does alleviate a recurrent burden, and because it's insightful to the point of being hyped, but not spoiled].
Whelp, SAO ended and ALO begins. We'll begin to see a branching out of interactions; SAO revolved around Kirito and Asuna, ALO is going to revolve around Kirito and another female. The best analogy revolves around Bakemongatari: Kirito is to Araragi as Asuna is to Senjougahara. Her presence is going to be attenuated, but their romance will never be compromised. Personally, I don't mind that [it makes the romantic, honeymoon episodes of SAO all the more sentimental].
Onto the controversial aspects of ALO: there is going to be a lot of rage. Rage directed towards one individual. One asinine, decadent, individual. I'm sure you'll be able to ascertain who this person is by the end of the first episode. This individual will play as the primary antagonist, but contrary to Heathcliff/Kayaba, he's a god damn idiot. It's a matter of pure potency versus intelligent strategy; Heathcliff went for strategy, this guy went for an unabashed exercise as power. The only solace is regardless of what he does do to Asuna, it'll never transcend to rape [really was looking for an euphemism, but I couldn't without sounding eight; personally, this is probably the most specific spoiler here, but it's a spoiler I'm sure most of the viewers will appreciate -- there's an influx of trolls speaking ambiguously about the topic; it doesn't happen, it's just heavily insinuated to occur (think of Shiki's situation in Kara no Kyoukai's seventh movie). There's also the matter of Asuna; in the SAO arc, she was painted to be a strong heroine. In ALO, she's essentially the damsel in distress; it's not incredibly irritating, it's just the developments that this specific attribute of her brings [see previous].
But ALO is hardly just a medium for rage. SAO excelled in developing a sentimental romance between the pair, ALO excels in applying logical mechanics with a more pragmatic game. SAO [the game] was probably enjoyable, but its primary selling point was its use of virtual reality -- it's relatively linear in progression, the most rudimentary type [Progressing from one floor to the next]. ALO will craft a more realistic type of game with more recurrent mechanics [SAO did very well with its incessant developing of the mechanics, but its core wasn't very creative]. In ALO, we'll see a more logical take on "what an MMORPG should be like." Anyways, let us begin with ALO; I doubt there'll be a lot of mechanics this episode. ALO takes part two months after the end of SAO.
[I'd use the spoiler tag, but it'd look extremely obnoxious with a spoiler this large]. I normally dislike blatant copy and pastes, but this was one where the overview for the entry and the reddit post essentially allign in interest.
Kirito: His character development is a little subtle. We do have to keep in mind that prior to entering Sword Art Online, he was the individualistic type [ergo a loner]. In SAO, his relationship with Asuna was incredibly important; I described them as having a symbiotic relationship, and that symbiosis continues. In SAO, Kirito developed numerous core values that we'll see exhibited in ALO. Even his basic interactions with Suguha is something to be awed; compare the reclusive older brother who doesn't care to talk with his younger sister, and the now, more talkative brother [Like I said, the character arcs (Lizbet, Sachi, and Scilica) in SAO weren't mediums for unabashed fan service, or filler episodes -- each encounter crafted a certain aspect of Kirito, we see Scilica's influence at work here].
Anyways, the ALO arc of SAO should be interesting. It won't be super enjoyable during some scenes, but for the rest, it keeps the mood of SAO and it continues with brilliant mechanics. The most irritating part of ALO for me was a certain character -- the author is great in making cliches complex; but he decided to go for the monochromatic route of an extreme evil. But, it won't kill the series.
Ironically, this episode was actually adapted very well. They added a few nuances that made the transition that much more smoother, they adapted it with some anachronisms [which resulted in it being better], and they managed to adapt some monologue into specific actions. They also showcased the second volume of the soundtrack; it's reminiscent of Fate/Zero's original soundtrack; the second season had a much better one.
Not a crucial entry to read, I already got most of my points across in this post. There's a few supplementary quotes, but aside from that, not a lot.